1. Field of the Invention
The present invention relates to thin-film magnetic heads and methods for making the same. In particular, the present invention relates to a thin-film magnetic head for a track width of 1 xcexcm or less and to a method for making the same.
2. Description of the Related Art
FIGS. 51 and 52 are a perspective view and a cross-sectional view, respectively, of a conventional floating thin-film magnetic head 150. The floating thin-film magnetic head 150 has a slider 151 and a combined thin-film magnetic head 157. Numeral 155 represents a leading side which is upstream of the moving direction of the slider 151 on a recording medium and numeral 156 represent a trailing side which is downstream of the moving direction. The slider 151 has an opposing face 152 which opposes the magnetic recording media, and the opposing face 152 has rails 151a and 151b which form air grooves 151c and 151c therebetween. The combined thin-film magnetic head 157 is provided on a trailing end 151d of the slider 151.
FIG. 53 is a perspective view of the combined thin-film magnetic head 157. With reference to FIGS. 52 and 53, the combined thin-film magnetic head 157 has a MR head h1 including a magnetoresistive element and a thin-film magnetic write head h2 deposited on the trailing end 151d of the slider 151.
The MR head h1 includes a lower shielding layer 163 composed of a magnetic alloy formed on the trailing end 151d of the slider 151, a lower gap layer 164 deposited on the lower shielding layer 163, a magnetoresistive element 165 partly exposed at the opposing face 152, an upper gap layer 166 covering the magnetoresistive element 165 and the lower gap layer 164, and an upper shielding layer 167 covering the upper gap layer 166. The upper shielding layer 167 also functions as a lower core layer of the thin-film magnetic write head h2.
The MR head h1 is used as a reading head. When a small fringing magnetic field from a recording magnetic medium is applied to the MR head h1, the resistance of the magnetoresistive element 165 changes. The MR head h1 detects a change in voltage based on the change in the resistance as reading signals from the magnetic recording medium.
The thin-film magnetic write head h2 includes the upper shielding layer or lower core layer 167, a gap layer 174 deposited on the upper shielding layer 167, a coil 176 formed in a back region Y of the gap layer 174, an upper insulating layer 177 covering the coil 176, and an upper core layer 178 which connects to the gap layer 174 in a magnetic pole end region X and to the upper shielding layer 167 in the back region Y.
The coil 176 has a planar spiral pattern. A bottom end 178c of the upper core layer 178 is magnetically coupled to the upper shielding layer 167 substantially in the center of the coil 176. The upper core layer 178 is covered with a protective layer 179 composed of alumina or the like.
The upper shielding layer 167, the gap layer 174, and the upper core layer 178 extend from the back region Y to the magnetic pole end region X and are exposed at the opposing face 152. The opposing face 152 has a magnetic gap of the gap layer 174 interposed between the upper core layer 178 and the upper shielding layer 167.
As shown in FIG. 52, in the magnetic pole end region X, the gap layer 174 is interposed between the upper core layer 178 and the lower core layer 167 in the vicinity of the opposing face 152. The back region Y lies behind the magnetic pole end region X.
The thin-film magnetic head h2 is a write head. When a recording current is applied to the coil 176, the recording current produces a magnetic flux in the upper core layer 178 and the upper shielding layer 167. The magnetic flux leaks as a fringing magnetic field from the magnetic gap toward the exterior. The fringing magnetic field magnetizes a magnetic recording medium to record signals.
In the production of the thin-film magnetic write head h2. however, the upper shielding layer 167 and the gap layer 174 are formed, and then the upper core layer 178 is formed by frame plating or the like so that the width thereof corresponds to the magnetic recording track width at the opposing face 152. The magnetic recording track width on the media can be reduced by decreasing t he magnetic recording track width of the thin-film magnetic write head h2, that is, the width of the upper core layer 178 exposed at the opposing face 152 at the magnetic pole end region. As a result, the track density on the magnetic recording medium and thus the recording density are improved.
When the magnetic recording track width is designed to be 1 xcexcm or less for high-density recording in the above thin-film magnetic head, the thickness of the laminate of the upper core layer 178, the gap layer 174, and the lower core layer 167 is significantly large with respect to the magnetic recording track width . If the thick laminate structure including the narrow upper core layer 178 is simultaneously formed by frame plating, the focal depth of exposure light is not matched during the formation of a resist frame, resulting in decreased resolution. Thus, the width of the upper core layer 178 is not constant at the edge, and a desired track width is not formed.
In order to achieve high-density recording by forming a magnetic recording track width of 1 xcexcm or less, a configuration shown in FIG. 54 is disclosed in U.S. Pat. Nos. 5,452,164 and 5,652,687.
FIG. 55 is an enlarged perspective view of a portion A in the magnetic pole end region X in the production process of a thin-film magnetic head 257 shown in FIG. 54. A groove 43 extending from the opposing face 152 is formed in an insulating layer 244. With reference to FIG. 56, a lower magnetic pole layer 167b as a part of the lower core layer 167, the gap layer 174, and an upper magnetic pole layer 178b as a part of the upper core layer 178 are deposited in that order by an electroplating process in the groove 43 to form the magnetic gap. The magnetic recording track width is controlled by determining the width of the groove 43.
The upper core layer 178 is connected to the upper magnetic pole layer 178b to complete a configuration shown in FIGS. 57 and 58, wherein FIG. 57 is a front view of the thin-film magnetic head 257 shown in FIG. 54 when viewed from the opposing face 152, and FIG. 58 is an enlarged cross-sectional view of the portion A of the thin-film magnetic head 257 in FIG. 54. As shown in FIG. 58, an edge portion of the lower magnetic pole layer 167b and the upper magnetic pole layer 178b at the back region Y defines a gap depth Gd.
As described above, the magnetic recording track width on the media can be reduced and recording densities on the magnetic recording media can be increased by decreasing the recording track width, that is, the width of the lower magnetic pole layer 167b, the gap layer 174, and the upper magnetic pole layer 178b. 
In the conventional thin-film magnetic write head h2, the lower magnetic pole layer 167b, the gap layer 174, and the upper magnetic pole layer 178b are deposited by electroplating in the groove 43. Thus, components for these layers are limited to materials which can be deposited by electroplating. On the other hand, use of high-performance magnetic materials for thin-film magnetic heads are required for achieving higher recording densities and miniaturization of magnetic recording media. In particular, a magnetic gap width of 1 xcexcm or less is required for achieving higher recording densities of magnetic recording media.
When the magnetic recording track width is decreased, as shown in FIG. 56, the face at the gap depth Gd is not necessarily formed to be parallel to the opposing face 152. With reference to FIG. 54, the groove 43 is generally formed in the insulating layer 244 by chemical etching. The corners of the groove 43, however, are rounded due to insufficient etching. With a narrow groove of 1 xcexcm or less, the distortion at the corners adversely affects the entire shape of the groove 43, particularly, the face at the gap depth Gd. In such a case, the fringing magnetic field increases, and thus, the recording efficiency of the thin-film magnetic head is decreased. Thus, the face at the gap depth Gd must be precisely formed.
Accordingly, objects of the present invention are:
(1) to allow the use of a variety of magnetic gap materials;
(2) to improve the recording efficiency of a thin-film magnetic head;
(3) to provide a thin-film magnetic head having a magnetic recording track width of 1 xcexcm or less which is applicable to a track width of 1 xcexcm or less on a magnetic recording medium;
(4) to provide a method for making a thin-film magnetic head having a magnetic recording track width of 1 xcexcm or less;
(5) to provide a thin-film magnetic head having a precise gap depth applicable to a track width of 1 xcexcm or less; and
(6) to provide a method for making a thin-film magnetic head having a precise gap depth applicable to a track width of 1 xcexcm or less.
According to a first aspect of the present invention, a thin-film magnetic head comprises an upper core layer and a lower core layer extending from a back region to a magnetic pole end region, the upper core layer and the lower core layer being exposed at an opposing face opposing a medium and being connected to each other in the back region, a coil provided on the periphery of the connection of the upper core layer and the lower core layer, a gap layer provided between the upper core layer and the lower core layer in the magnetic pole end region, an insulating layer formed on the lower core layer, and a groove formed in the magnetic pole end region of the insulating layer and extending from the opposing face to the back region. The groove forms an opening in the lower core layer, the upper core. layer, and the opposing face, and has a main portion having a cross-sectional size which is substantially the same as the size of the opening at the opposing face. The lower magnetic layer, the gap layer, and the upper magnetic layer are deposited in the groove. The lower magnetic pole layer is in contact with the lower core layer and the upper magnetic pole layer is in contact with the upper core layer so that the upper magnetic pole layer constitutes an upper magnetic pole end and the lower magnetic pole layer constitutes a lower magnetic pole end. Moreover, in the exposed section at the opposing face, the length of the lower magnetic pole layer in the track width direction is larger than the length of the upper magnetic pole layer in the track width direction.
In such a configuration, the magnetic gap width can be reduced to a submicron order of 1 xcexcm or less by reducing the width of the groove.
Preferably, the groove has an adjoining portion extending from the main portion to a part of the back region.
Preferably, a back insulating layer is deposited in the back region of the gap layer.
Preferably, at the opposing face, the difference between the length of the lower magnetic pole layer in the track width direction and the length in the track width direction of the upper magnetic pole layer in contact with the gap layer is equal to or less than the thickness of the gap layer.
Preferably, the adjoining portion extending to the back region has a cross-sectional size which is substantially the same as that of the main portion. Alternatively, the cross-sectional size of the adjoining portion extending to the back region may gradually increase in the track width direction of the lower core layer.
Preferably, the back insulating layer has a sloping face so that the thickness of the back insulating layer increases toward the back region.
The lower magnetic pole layer and the gap layer may be deposited in the magnetic pole end region and the back region of the groove, and the upper magnetic pole layer may be deposited in the magnetic pole end region of the groove. The back end of the upper magnetic pole layer may define the gap depth.
This configuration can exactly determine the distance between the opposing face and the back end of the upper magnetic pole layer. Thus, the gap depth is exactly defined.
Preferably, the length of the upper magnetic pole layer from the opposing face, that is, the gap depth, is equal to or larger than the width of the upper magnetic pole layer.
A coil insulating layer may be deposited on the back insulating layer and may have a sloping face toward the sloping face of the back insulating layer. The coil insulating layer can expand the distance between the lower core layer and the upper core layer in the back region of the groove. Thus, the fringing magnetic flux from the upper core layer to the lower core layer is reduced. Accordingly, overwrite characteristics and recording efficiency of the magnetic head are improved.
Preferably, the gap layer comprises metal.
Preferably, each of the upper magnetic pole layer and the lower magnetic pole layer comprises one alloy selected from the group consisting of a Ni-Fe alloy; a Nixe2x80x94Fexe2x80x94Nb alloy; a Coxe2x80x94Fe alloy; a Coxe2x80x94Fexe2x80x94Ni alloy; a Coxe2x80x94Fexe2x80x94Nixe2x80x94X alloy wherein X is at least one element selected from the group consisting of Mo, Cr, Pd, B, and In; a Coxe2x80x94Zrxe2x80x94Nb alloy; a Coxe2x80x94Hfxe2x80x94Nb alloy; an Fexe2x80x94Mxe2x80x94C alloy wherein M is at least one element selected from the group consisting of Hf, Zr, Ti, V, Nb, Ta, Cr, Mo, and W; a Txe2x80x94Xxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy wherein T is at least one element of Fe and Co, X is at least one element of Si and Al, M is at least one element selected from the group consisting of Ti, Zr, Hf, V, Ta, Mo, and W, Z is at least one element of C and N, and Q is at least one element selected from the group consisting of Cr, Re, Rh, Ni, Pd, Pt, and Au; a Txe2x80x94Sixe2x80x94Alxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy wherein T is at least one element of Fe and Co, M is at least one element of Zr, Hf, Nb, and Ta, Z is at least one element of C and N, and Q is at least one element selected from the group consisting of Cr, Ti, Mo, W, V, Re, Ru, Ni, Pd, Pt, and Au: and an Fexe2x80x94Mxe2x80x94O alloy wherein M is at least one element selected from the group consisting of Hf, Zr, Ti, V, Nb, Ta, Cr, Mo, and W.
The Nixe2x80x94Fe alloy represented by the formula NixFey preferably satisfies the following relationships in which x and y are atomic percent:
86xe2x89xa6xxe2x89xa692, 8xe2x89xa6yxe2x89xa614, and x+y=100.
This soft magnetic alloy exhibits superior soft magnetism and is suitable for the core of the thin-film magnetic head.
The Nixe2x80x94Fexe2x80x94Nb alloy represented by the formula NixFeyNbz preferably satisfies the following relationships in which x, y and z are atomic percent:
76xe2x89xa6xxe2x89xa684, 8xe2x89xa6yxe2x89xa615, 5xe2x89xa6zxe2x89xa612, and x+y+z=100.
This soft magnetic alloy also exhibits superior soft magnetism and is suitable for the core of the thin-film magnetic head. Moreover, the Nixe2x80x94Fexe2x80x94Nb alloy exhibits a higher resistivity than that of the Nixe2x80x94Fe alloy, reduces eddy current loss, and improves high-frequency recording characteristics.
The Coxe2x80x94Fe alloy represented by the formula CoxFey preferably satisfies the following relationships in which x and y are atomic percent:
86xe2x89xa6xxe2x89xa692, 8xe2x89xa6yxe2x89xa614, and x+y=100.
This soft magnetic alloy exhibits superior soft magnetism and is suitable for the core of the thin-film magnetic head. Moreover, the Coxe2x80x94Fe alloy exhibits higher saturation magnetic flux density and higher resistivity than those of the Nixe2x80x94Fexe2x80x94Nb alloy. Thus, this alloy reduces eddy current loss, increases the recording density, and improves high-frequency recording characteristics.
The Coxe2x80x94Fexe2x80x94Ni alloy represented by the formula CoxFeyNiz preferably satisfies the following relationships in which x, y and z are weight percent:
0.1xe2x89xa6xxe2x89xa615, 38xe2x89xa6yxe2x89xa660, 40xe2x89xa6zxe2x89xa662, and x+y+z=100.
This soft magnetic alloy also exhibits superior soft magnetism and is suitable for the core of the thin-film magnetic head. Moreover, the Coxe2x80x94Fexe2x80x94Ni alloy exhibits a higher saturation magnetic flux density and higher resistivity than those of the Nixe2x80x94Fexe2x80x94Nb alloy and the Coxe2x80x94Fe alloy, reduces eddy current loss, increases the recording density, and improves high-frequency recording characteristics.
The Coxe2x80x94Fexe2x80x94Nixe2x80x94X alloy, in which X is at least one element selected from the group consisting of Mo, Cr, Pd, B, and In, represented by the formula CoxFeyNizXw preferably satisfies the following relationships in which x, y, z and w are weight percent:
0.1xe2x89xa6xxe2x89xa615, 38xe2x89xa6yxe2x89xa660, 40xe2x89xa6zxe2x89xa662, 0.1xe2x89xa6wxe2x89xa63, and x+y+z+w=100.
This soft magnetic alloy also exhibits superior soft magnetism and is suitable for the core of the thin-film magnetic head. Moreover, this Coxe2x80x94Fexe2x80x94Nixe2x80x94X alloy exhibits higher resistivity than that of the Coxe2x80x94Ni alloy, and significantly reduces eddy current loss which is advantageous for high-frequency recording. In addition, the Coxe2x80x94Fexe2x80x94Nixe2x80x94X alloy exhibits a saturation magnetic flux density which is comparable to that of the Coxe2x80x94Fexe2x80x94Ni alloy and is suitable for high-density recording.
The Coxe2x80x94Zrxe2x80x94Nb alloy represented by the formula CoxZryNbz preferably satisfies the following relationships in which x, y, and z are atomic percent:
1.5xe2x89xa6yxe2x89xa613, 6.5xe2x89xa6zxe2x89xa615, 1xe2x89xa6(y/z)xe2x89xa62.5, and x+y+z=100.
This soft magnetic alloy exhibits significantly superior soft magnetism and is suitable for the core of the thin-film magnetic head, since this alloy does not exhibit crystalline magnetic anisotropy when the core is deposited.
The Coxe2x80x94Hfxe2x80x94Nb alloy represented by the formula CoxHfyNbz preferably satisfies the following relationships in which x, y, and z are atomic percent:
1.5xe2x89xa6yxe2x89xa613, 6.5xe2x89xa6zxe2x89xa615, 1xe2x89xa6(y/z)xe2x89xa62.5, and x+y+z=100.
This soft magnetic alloy also exhibits significantly superior soft magnetism and is suitable for the core of the thin-film magnetic head, since this alloy does not exhibit crystalline magnetic anisotropy when the core is deposited.
The Fexe2x80x94Mxe2x80x94C alloy is composed of a crystalline phase essentially consisting of Fe and a crystalline phase of carbide of at least one element selected from the group consisting of Hf, Zr, Ti, V, Nb, Ta, Cr, Mo, and W. On the whole, the alloy-is preferably composed of fine crystallites having an average crystal grain size of 40 nm or less. Preferably, the average crystal grain size d of the carbide and the average crystal grain size D of the Fe crystal satisfy the relationship 0.05xe2x89xa6d/Dxe2x89xa60.4.
More preferably, the Fexe2x80x94Mxe2x80x94C alloy represented by the formula FexMyCz preferably satisfies the following relationships in which x, y, and z are atomic percent:
50xe2x89xa6xxe2x89xa696, 2xe2x89xa6yxe2x89xa630, 0.5xe2x89xa6zxe2x89xa625 and x+y+z=100.
This soft magnetic alloy also exhibits significantly superior soft magnetism and is suitable for the core of the thin-film magnetic head, since crystalline magnetic anisotropy is extremely low due to fine crystal grains which are formed by precipitation of M carbide. Since this alloy exhibits a higher saturation magnetic flux density and a lower coercive force than those of the above alloys, the soft magnetism is more satisfactory and is suitable for high-density recording. Moreover, the precipitated M carbide contributes to improved heat resistance.
The Txe2x80x94Xxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy is composed of a crystalline phase essentially consisting of Fe or Co and a crystalline phase of a carbide or a nitride of at least one element selected from the group consisting of Ti, Zr, Hf, V, Ta, Mo, and W. On the whole, the alloy is preferably composed of fine crystallites having an average crystal grain size of 40 nm or less. Preferably, the average crystal grain size d of the carbide or nitride and the average crystal grain size D of the Fe or Co crystal satisfy the relationship 0.05xe2x89xa6d/Dxe2x89xa60.4.
More preferably, the Txe2x80x94Xxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy represented by the formula TaXbMcZdQe, in which T is at least one element of Fe and Co, X is at least one element of Si and Al, and M is at least one element selected from the group consisting of Ti, Zr, Hf, V, Ta, Mo, and W, preferably satisfies the following relationships in which a, b, c, d, and e are atomic percent:
0xe2x89xa6axe2x89xa625, 0xe2x89xa6bxe2x89xa625, 1xe2x89xa6cxe2x89xa610, 5xe2x89xa6dxe2x89xa615, 0xe2x89xa6exe2x89xa610, and a+b+c+d+e=100.
This soft magnetic alloy also exhibits significantly superior soft magnetism and is suitable for the core of the thin-film magnetic head. Moreover, the X component increases the resistivity of the alloy to a level of 120 xcexcxcexa9cm or more, which is higher than that of the Fexe2x80x94Mxe2x80x94C alloy. Thus, this alloy exhibits small eddy current loss and is suitable for high-frequency recording. The X component contributes to improved corrosion and oxidation resistance compared to the Fexe2x80x94Mxe2x80x94C alloy.
The Txe2x80x94Sixe2x80x94Alxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy is composed of a body centered cubic fine crystalline phase essentially consisting of Fe or Co and having an average crystal grain size of 40 nm or less and a crystalline phase of a carbide or a nitride of at least one element selected from the group consisting of Ti, Zr, Hf, Nb, and Ta which is precipitated at the grain boundaries of the fine crystalline phase, wherein at least one element of Si and Al and at least one element selected from the group consisting of Cr, Ti, Mo, W, V, Re, Ru, RH, Ni, Pd, Pt, and Au are dissolved in the body centered cubic crystalline phase.
More preferably, the Txe2x80x94Sixe2x80x94Alxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy represented by the formula TaSibAlcMdZeQf, in which T is at least one element of Fe and Co, M is at least one element of Zr, Hf, Nb, and Ta, Z is at least one element of C and N, and Q is at least one element selected from the group consisting of Cr, Ti, Mo, W, V, Re, Ru, Ni, Pd, Pt, and Au, preferably satisfies the following relationships in which a, b, c, d, e, and f are atomic percent:
8xe2x89xa6bxe2x89xa615, 0xe2x89xa6cxe2x89xa610, 1xe2x89xa6dxe2x89xa610, 1xe2x89xa6exe2x89xa610, 0xe2x89xa6fxe2x89xa615, and a+b+c+d+e+f=100.
This soft magnetic alloy also exhibits superior soft magnetism and is suitable for the core of the thin-film magnetic head. Moreover, this alloy containing both Si,and Al has an absolute value of magnetostriction which is smaller than that of the Txe2x80x94Xxe2x80x94Mxe2x80x94Zxe2x80x94Q alloy. Thus, this alloy exhibits decreased internal stress and is resistant to changes in temperature.
The Fexe2x80x94Mxe2x80x94O alloy represented by the formula FeaMbOc, in which M is at least one element selected from the group consisting of Hf, Zr, Ti, V, Nb, Ta, Cr, Mo, and W, preferably satisfies the following relationships in which a, b, and c are atomic percent:
50xe2x89xa6axe2x89xa670, 5xe2x89xa6bxe2x89xa630, 10xe2x89xa6cxe2x89xa630, and a+b+c=100.
This soft magnetic alloy also exhibits significantly superior soft magnetism, that is, low coercive force, and is suitable for the core of the thin-film magnetic head, since this alloy does not exhibit crystalline magnetic anisotropy. Moreover, this alloy exhibits a higher resistivity of 400 to 2xc3x97105 xcexcxcexa9cm, contributes to a significant decrease in eddy current loss, and improves recording characteristics in high-frequency regions of several tens of MHz.
The upper face of the lower core layer may be planarized by polishing. The tilt angle of the tapered sections of the said walls is preferably in a range of 10 degrees to 80 degrees with respect to the upper face of the lower core layer. The tilt angle of the sloping face of the back insulating layer is preferably in a range of 10 degrees to 80 degrees with respect to the lower core layer. The back insulating layer may extend from the insulating layer.
Since a tapered portion is formed on the upper core layer at the upper magnetic pole layer side, a magnetic flux between the upper core layer and the lower core layer becomes smooth and the fringing magnetic flux at the junction between the upper core layer and the lower core layer can be reduced.
The upper face of the lower core layer has a surface roughness Ra of 0.001 to 0.015 xcexcm by planarization. Thus, the groove can be precisely formed and the magnetic recording track width can be reduced.
The insulating layer preferably comprises at least one material selected from the group consisting of AlO, Al2O3, SiO; SiO2, Ta2O5, TiO, AlN, AlSiN, TiN, SiN, Si3N4, NiO, WO, WO3, BN, and CrN. The insulating layer may have a single-layer configuration or a multi-layer configuration of these materials. When the insulating layer is not etched, the insulating layer may be B4C, sialon, or SiC.
The gap layer preferably comprises at least one material selected from the group consisting of Au, Pt, Rh, Pd, Ru, Cr, NiMo alloys, NiW alloys, NiP alloys, and NiPd alloys. The gap layer may have a single-layer configuration or a multi-layer configuration of these materials. Since these materials are nonmagnetic materials and are not magnetized, these can be preferably used in the gap layer of the thin-film magnetic head. When electroplating is not employed, the gap layer preferably comprises at least one material selected from the group consisting of AlO, Al2O3, SiO, SiO2, Ta2O5, TiO, AlN, AlSiN, TiN, SIN, Si3N4, NiO, WO, WO3, BN, CrN, B4C, sialon, and SiC. The gap layer may have a single-layer configuration or a multi-layer configuration of these materials.
Preferably, the width of the main portion of the groove is 1 xcexcm or less.
According to a second aspect of the present invention, a combined thin-film magnetic head comprises a magnetic read head having a magnetoresistive element, and the thin-film magnetic head according to the first aspect.
Preferably, the insulating layer, the lower magnetic pole layer, the gap layer, and the upper magnetic pole layer are exposed at the opposing face. Since the magnetic recording track width agrees with the width of the groove in the insulating layer at the opposing face, the magnetic recording track width can be reduced. Since the magnetic gap is exposed at the opposing face, magnetic recording on a magnetic recording medium can be effectively performed by a fringing magnetic field from the magnetic gap.
According to a third aspect of the present invention, a method for making a thin-film magnetic head, which comprises an upper core layer and a lower core layer extending from a back region to a magnetic pole end region, the upper core layer and the lower core layer being exposed at an opposing face opposing a medium and being connected to each other in the back region, a coil provided on the periphery of the connection of the upper core layer and the lower core layer, and a gap layer provided between the upper core layer and the lower core layer in the magnetic pole end region, comprises the steps of planarizing the upper face of the lower core layer by polishing, depositing the lower magnetic pole layer, the gap layer, and the upper magnetic pole layer on the lower core layer so that the lower core layer connects to the lower magnetic pole layer, removing parts of the lower magnetic pole layer, the gap layer, and the upper magnetic pole layer, and depositing an insulating layer on the lower core layer exposed by the removing step, forming a gap depth, which is substantially parallel to the opposing surface, in the upper magnetic pole layer, forming a coil in the back region, and forming an upper core layer connecting the upper magnetic pole layer in the magnetic pole end region and covering a part of the coil in the back region.
By planarization of the lower core layer, the insulating layer deposited on the subsequent step is also planarized and can be precisely formed by anisotropic etching. As a result, the magnetic gap width can be reduced.
When the lower magnetic pole layer, the gap layer, and the upper magnetic pole layer are formed by anisotropic etching, the width to the thickness of these layers can be precisely determined without side etching.
Preferably, a mask layer extending from the exterior of the opposing face to the magnetic pole end region is formed on the upper magnetic pole layer, and parts of the lower magnetic pole layer, the gap layer, and the upper magnetic pole layer are removed by anisotropic etching.
The mask layer may have a mask main portion having the same size as the size of the magnetic gap at the opposing face and extending in the magnetic pole end region.
The mask layer may be formed on the upper magnetic pole layer from the magnetic pole end region to a part of the back region, and a back insulating layer may be formed on the gap layer in the back region.
The mask layer may comprise the mask main portion and an adjoining mask portion extending from the mask main portion to the back region.
Preferably, an upper mask layer is formed on the upper magnetic pole layer, and then the upper magnetic pole layer is subjected to ion milling to form the gap depth.
Preferably, the back insulating layer has a sloping face which lies in the back region on the gap layer and slopes so as to increase the thickness thereof from the opposing face to the back region, and the sloping face is formed by sputtering or ion beam sputtering while maintaining the upper mask layer on the upper magnetic pole layer and then by removing the upper mask layer.
Preferably, the width of the mask layer at the opposing face is 1 xcexcm or less.
Preferably, the insulating layer is formed by sputtering or ion beam sputtering while maintaining the mask layer on the upper magnetic pole layer and then by removing the mask layer.
Preferably, at the opposing face, the difference between the length in the track width direction of the lower magnetic pole layer in contact with the gap layer and the length in the track width direction of the upper magnetic pole layer in contact with the gap layer is equal to or smaller than the thickness of the gap layer.
Preferably the gap layer comprises an inorganic insulating material.
The gap layer preferably comprises at least one material selected from the group consisting of AlO, Al2O3, SiO, SiO2, Ta2O5, TiO, AlN, AlSiN, TiN, SiN, Si3N4, NiO, WO, WO3, BN, CrN, B4C, sialon, and SiC. The gap layer may have a single-layer configuration or a multi-layer configuration of these materials. The gap layer can be formed by a sputtering or ion beam sputtering process which is superior to an electroplating process in reproducibility and uniformity of the resulting film.
Moreover, an RF sputtering process and an ion beam sputtering process can deposit a metal material and an insulating material. Since the thickness of the insulating material on the substrate can be measured by a non-contacting thickness meter, the quality control of the product can be readily performed.
Preferably, the thickness of the lower magnetic pole layer is at least 0.1 xcexcm, and is at least 0.5 times the thickness of the gap layer.
A coil insulating layer having a sloping face toward the sloping face of the back insulating layer may be formed on the back insulating layer.